Air disk brakes have been widely adopted in Europe, primarily as result of their performance advantages over conventional drum brakes. These high-performance brakes are now being widely adopted in U.S. commercial vehicles and industry experts predict air disc braking systems will consume 30% of the US commercial vehicle market by 2020. One major problem faced by users of these brake calipers is their inherent ability to seize up and cause brake failure during service. Air disc calipers, like most brake calipers, comprise two-pieces of iron. One piece known as the carrier, saddle, or bracket, and is bolted to the wheel end in a fixed position. For the purposes of this discussion, we shall hereafter refer to this as the carrier. The second piece of iron is known as the caliper head or caliper body. It contains the mechanical components that receive actuation from an actuating mechanism (i.e. air chamber), and then converts the force from the actuator into mechanical leverage that operates pistons or threaded tappets. Those pistons or tappets then advance to create brake torque. No brake torque or clamping force can be created unless the caliper head can be pulled into the carrier in such a manner as to create the clamping force necessary for the brake pads to clamp the brake disc and retard the vehicle motion. To affect this free motion between the caliper head and carrier, original equipment manufacturers have designed the caliper with a guide pin assembly (sometimes also referred to as a slide pin or slide pin assembly). This assembly consists generally of one or more bushings that fit inside a bore on the caliper head. These bushings may be made of bronze, brass or steel and may or may not be dimpled. A lubricated steel guide pin is then inserted into the bushing. This guide pin is then bolted into the carrier, attaching the carrier to the caliper head, and providing a mechanism for lateral travel from which clamping force can be derived. Between the carrier and the caliper head is a rubber boot that seals the guide pin assembly on one end. At the back end of the caliper is a metal sealing cap that is pressed into the caliper to seal the guide pin assembly. All major manufacturers of calipers use this same process for the guide pin or slide pin assembly. In all cases, their design is defective and such defect results in extremely high maintenance costs for commercial vehicle fleets, and potential catastrophic brake failure for individual vehicles. The cause of this failure is that original equipment (OE) manufacturers have engineered calipers so that they cannot be regularly lubricated and maintained in such a manner as to extend the life of the guide pin assembly. As a result, the high-performance caliper will operate at temperatures exceeding 1,500 degrees Fahrenheit, and will constantly endure torque loads of more than 15,000 lb-ft. The combination of this high temperature and high torque causes the grease in the guide pin mechanism to literally evaporate, thus ceasing lubrication between the caliper head and carrier. Because there is no mechanism to service the unit (short of a complete replacement of the guide pin assemblies), the caliper continues to deteriorate until it seizes and creates exceptionally high costs of replacement, or catastrophic brake failure.
It is therefore an objective of the present invention to provide a caliper guide pin assembly which allows more lubrication to be delivered to the guide pin and bushing of a caliper head and allows the guide pin and bushing to be continually serviced on an ongoing basis therefore improving the fatigue life of the caliper. The present invention includes a guide pin with a plurality of channels at the lateral portion which allow a greater volume of lubrication to be introduced into the guide pin assembly on first application thereby increasing assembly life and decreasing fatigue. The present invention also includes a lubrication directional plug and a sealing end cap. The lubrication directional plug directs the lubrication through the guide pin assembly. The sealing end cap includes a grease valve to prevent over-lubrication of the guide pin assembly and zerk fitting allowing guide pin assembly to receive lubrication.